Enum in C

What is Enum in C ?

An enum (short for “enumeration”) in C is a user-defined data type that consists of a set of named integral constants, known as enumerator values or simply enumerators. Enumerations are used to define a set of named integer values that represent distinct elements within a group. Enums make your code more readable and maintainable by giving meaningful names to numeric constants.

Here’s the syntax for declaring an enum in C:

enum enum_name {
    // More enumerators

Now, let’s provide two examples of enums in C, along with code, output, and explanations.

Examples of Enum in C

Example 1: Days of the Week

#include <stdio.h>

enum DaysOfWeek {

int main() {
    enum DaysOfWeek today = Wednesday;
    printf("Today is %d\n", today);
    return 0;


Today is 3

Explanation: In this example, we define an enum DaysOfWeek that represents the days of the week. By default, the first enumerator Sunday has a value of 0, and subsequent enumerators have values incremented by 1. In the main function, we declare a variable today of type enum DaysOfWeek and initialize it with Wednesday. When we print the value of today, it outputs 3 because Wednesday is the fourth enumerator, and it has a value of 3.

Example 2: RGB Colors

#include <stdio.h>

enum RGBColor {
    Red = 0xFF0000,
    Green = 0x00FF00,
    Blue = 0x0000FF

int main() {
    enum RGBColor myColor = Red;
    printf("My favorite color is 0x%X\n", myColor);
    return 0;


My favorite color is 0xFF0000

Explanation: In this example, we define an enum RGBColor representing RGB colors with hexadecimal values. Each enumerator is assigned a specific integer value, which in this case, represents the corresponding color’s hexadecimal code. In the main function, we declare myColor as an enum RGBColor and initialize it with Red. When we print myColor, it outputs 0xFF0000, which is the hexadecimal value for the color red.

Mistakes to Avoid When Using Enums in C:

  1. Using duplicate enumerator names: Each enumerator within an enum should have a unique name. Using duplicate names can lead to compilation errors and confusion.
  2. Assuming specific integer values: While you can assign values to enum constants, it’s generally better to let the compiler assign values automatically. Relying on specific integer values can make your code less readable and more error-prone.
  3. Mixing enum types: Avoid mixing variables of different enum types as it can lead to unintended consequences and make the code harder to understand.
  4. Not handling undefined enum values: If you perform operations that might result in undefined enum values (e.g., adding or subtracting), make sure to handle such cases gracefully to prevent unexpected behavior.
  5. Not using enums for related constants: Enums are designed for grouping related constants. If you have a set of related values, it’s better to use an enum rather than defining them as separate constants.